Alpha-2-Delta Ligand — Neuropathic Pain / Epilepsy Adjunct Pregnancy: Gabapentin crosses the human placenta; there is a limited amount of data from use in pregnant women, and animal studies have shown reproductive toxicity, so gabapentin should not be used during pregnancy unless the potential benefit to the mother clearly outweighs the potential risk to the foetus. The risk of birth defects is increased 2-3 fold in offspring of mothers treated with any antiepileptic medicinal product; monotherapy should be practised whenever possible and antiepileptic therapy must not be stopped suddenly, as breakthrough seizures could have serious consequences for mother and child. Neonatal withdrawal syndrome has been reported in newborns exposed in utero, with a possible increased risk on co-exposure with opioids — monitor newborns carefully. Breast-feeding: gabapentin is excreted in human milk and the effect on the breast-fed infant is unknown; use only if the benefits clearly outweigh the risks. No effect on fertility in animal studies.

Gabapentin

Brand names: Neurontin

Gabapentin is a gabapentinoid anticonvulsant used for focal epilepsy and for peripheral neuropathic pain.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Epilepsy (adults and adolescents 12 years and above): effective dosing range 900 to 3600 mg/day. Initial titration: Day 1 300 mg once a day, Day 2 300 mg two times a day, Day 3 300 mg three times a day — or 300 mg three times a day from Day 1

Route: Oral — may be given with or without food; swallow whole with sufficient fluid intake (e.g. a glass of water)

Frequency: Three times a day (the total daily dose divided into three single doses); the maximum time interval between doses should not exceed 12 hours to prevent breakthrough convulsions

Max: 3600 mg/day maximum. Dosages up to 4800 mg/day have been well tolerated in long-term open-label clinical studies

TITRATION (all indications): after initiation the dose may be increased in 300 mg/day increments every 2-3 days up to the maximum of 3600 mg/day; slower titration may be appropriate for individual patients. Minimum time to reach 1800 mg/day is one week, to reach 2400 mg/day a total of 2 weeks, and to reach 3600 mg/day a total of 3 weeks. Plasma concentration monitoring is not necessary, and gabapentin may be combined with other antiepileptics without concern for altered plasma/serum concentrations. PERIPHERAL NEUROPATHIC PAIN (adults): initiate with the Day 1-3 titration above, or alternatively start at 900 mg/day given as three equally divided doses, then increase in 300 mg/day increments every 2-3 days up to a maximum of 3600 mg/day. Efficacy and safety have not been examined in clinical studies for treatment periods longer than 5 months; if dosing beyond 5 months is required the treating physician should assess the patient's clinical status and the need for additional therapy. DISCONTINUATION: if gabapentin has to be stopped, this should be done gradually over a minimum of 1 week, independent of the indication. POOR GENERAL HEALTH (e.g. low body weight, after organ transplantation): titrate more slowly, using smaller dosage strengths or longer intervals between increases. ELDERLY (over 65 years): may require dosage adjustment because of declining renal function (see renalAdjustment); somnolence, peripheral oedema and asthenia may be more frequent. HAEMODIALYSIS: for anuric patients on haemodialysis who have never received gabapentin, a loading dose of 300 to 400 mg, then 200 to 300 mg following each 4 hours of haemodialysis, is recommended, with no treatment on dialysis-free days; for renally impaired patients on haemodialysis, base the maintenance dose on the renal table and give an additional 200 to 300 mg dose after each 4-hour haemodialysis session. Source product: Gabapentin 100 mg hard capsules (UK SPC).

Paediatric dose

Route: Oral

Frequency: Total daily dose divided into three single doses; the maximum time interval between doses should not exceed 12 hours

Epilepsy, paediatric population aged 6 years and above: the starting dose should range from 10 to 15 mg/kg/day, and the effective dose is reached by upward titration over a period of approximately three days; the effective dose in children aged 6 years and older is 25 to 35 mg/kg/day. Dosages up to 50 mg/kg/day have been well tolerated in a long-term clinical study — the SPC states no absolute paediatric maximum, so no maxDose is recorded here (a per-kg figure must never be used as a total-dose ceiling). dosePerKg is deliberately null because the SPC states ranges, not a single figure, and reducing it to one number would misrepresent the label. This SPC gives no paediatric dose for peripheral neuropathic pain. Confirm against a children's formulary before prescribing.

Dose adjustments

Renal

Dosage adjustment is recommended in patients with compromised renal function (total daily dose, administered as three divided doses): creatinine clearance >=80 ml/min, 900-3600 mg/day; 50-79 ml/min, 600-1800 mg/day; 30-49 ml/min, 300-900 mg/day; 15-29 ml/min, 150-600 mg/day; <15 ml/min, 150-300 mg/day. The 150 mg figure is to be administered as 300 mg every other day. For creatinine clearance below 15 ml/min the daily dose should be reduced in proportion to creatinine clearance (e.g. a patient with a clearance of 7.5 ml/min should receive one-half the daily dose of a patient with a clearance of 15 ml/min). See adultDose notes for the haemodialysis regimen.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients listed in section 6.1

Side effects

Somnolence, dizziness and ataxia — very common (>=1/10); viral infection — very common
Convulsions, hyperkinesias, dysarthria, amnesia, tremor, insomnia, headache, paraesthesia, hypaesthesia, abnormal coordination, nystagmus, altered reflexes — common
Nausea, vomiting, diarrhoea, abdominal pain, dyspepsia, constipation, dry mouth or throat, flatulence, dental abnormalities, gingivitis — common; anorexia and increased appetite — common
Hostility, confusion, emotional lability, depression, anxiety, nervousness, abnormal thinking — common; hallucinations, suicidal ideation and drug dependence — frequency not known
Serious/rare: anaphylaxis and hypersensitivity syndrome (fever, rash, hepatitis, lymphadenopathy, eosinophilia), Stevens-Johnson syndrome and toxic epidermal necrolysis, pancreatitis, hepatitis and jaundice, respiratory depression (rare), loss of consciousness (rare), thrombocytopenia and hyponatraemia (not known)

Interactions

NOTE ON PROVENANCE: the UK SPC section 4.5 was not captured in this fetch. The first entry below is from UK SPC section 4.4; the remainder are from the US prescribing information section 7 and must be checked against the UK SPC section 4.5.
Opioids and other CNS depressants — patients requiring concomitant CNS depressants, including opioids, should be carefully observed for signs of CNS depression such as somnolence, sedation and respiratory depression (UK SPC section 4.4)
Opioids (morphine, hydrocodone, oxycodone, buprenorphine) — respiratory depression and sedation, sometimes resulting in death, have been reported following co-administration with gabapentin (US label section 7.1)
Hydrocodone — co-administration with gabapentin decreases hydrocodone exposure; consider the potential for altered hydrocodone exposure and effect when gabapentin is started or stopped (US label section 7.1)
Antacids containing aluminium and magnesium hydroxides — mean gabapentin bioavailability reduced by about 20%; take gabapentin at least 2 hours after the antacid (US label section 7.3)
Other antiepileptic drugs — gabapentin is not appreciably metabolised and does not interfere with the metabolism of commonly co-administered antiepileptic drugs (US label section 7.2)

Clinical monograph

How it works

It binds the alpha-2-delta subunit of voltage-gated calcium channels, reducing presynaptic calcium influx and the release of excitatory neurotransmitters.

Prescribing in practice

Gabapentin is a controlled drug with recognised abuse potential and risk of fatal respiratory depression, especially when combined with opioids or other CNS depressants or in respiratory compromise.
Doses require titration to minimise sedation and dizziness, and the dose must be reduced in renal impairment as it is cleared unchanged by the kidneys.
Withdraw gradually to avoid rebound seizures and a discontinuation syndrome.

Monitoring

Monitor for sedation, mood or behavioural change including suicidal ideation, and review renal function as a guide to dosing.

Counselling the patient

Do not stop suddenly; the dose should be tapered under medical supervision.
Avoid alcohol and be cautious with driving until you know how it affects you.
Report low mood, thoughts of self-harm or excessive drowsiness.

Evidence & guidelines

MHRA reclassified gabapentin as a controlled drug and has warned of the risk of respiratory depression when combined with other CNS depressants.

Reference: MHRA 2019 Gabapentinoids Controlled Drug Classification; MHRA 2017 Opioid/Gabapentinoid Respiratory Depression Warning; NICE CG173 (Neuropathic Pain); Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways